The present invention is directed to purge apparatus for the removal of accumulated moisture, air and other non-condensibles from the system refrigerant in chillers that provide chilled water for use in industrial processes and to comfort condition buildings. More specifically, this invention relates to purge apparatus of the "thermal" type which efficiently removes air, water and other non-condensibles from refrigerant chillers, most commonly of the centrifugal type, in a manner which minimizes the loss of chiller system refrigerant from the chiller.
Certain refrigerant chillers utilize low pressure refrigerants, such as the refrigerant commonly referred to as R11, and include components which, under certain conditions, operate at less than atmospheric pressure. This is in contrast to chillers employing "high" pressure refrigerants, such as the refrigerants commonly referred to as R12 and R22, which normally operate with condensing pressures in excess atmospheric pressure.
Because refrigerant chillers using low pressure refrigerants include components which operate at less than atmospheric pressure it is possible for moisture, air and other non-condensibles to leak into these machines through, for instance, flare fittings and gasketed surfaces located on the low pressure side of the chiller. Water vapor will also potentially enter the low pressure side of a chiller entrained in air or through chiller condenser tube leaks.
If allowed to accumulate, non-condensible elements become trapped in the chiller condenser. The presence of these elements in the condenser increases condensing pressure and therefore chiller compressor power requirements thereby reducing chiller efficiency and cooling capacity. Additionally, if this situation is untreated, chillers will typically surge, cutout or fail to start. Finally, the failure to remedy the presence non-condensibles within the chiller can lead to increased corrosion throughout the chiller.
The need therefore exists to provide purge apparatus which removes moisture, air and other non-condensibles from a refrigerant chiller. While many purge system designs exist, there continues to be a need to provide purge apparatus which efficiently expels non-condensibles from refrigerant chillers while minimizing the loss of chiller refrigerant in the process of removing such non-condensibles and which is operative independent of the operational status of the chiller with which it is used.